The long-range objective of this research project is to better understand how mitochondrial ATPase participates in the process of ATP synthesis and in the process of ATP utilization in both normal and neoplastic cells. Special emphasis is being given to molecular studies of the ATPase complex of normal cells in an attempt to elucidate the mechanism of ATP synthesis and ATP utilization, and to understand how these two processes are regulated. Emphasis is being given also to molecular studies of the ATPase complex of neoplastic cells in order to ascertain whether ATP synthesis or ATP utilization, or the regulation of these two activities has been altered in any way during transformation. To meet these objectives we are studying the structural and catalytic properties of the oligomycin-sensitive ATPase of normal and neoplastic tissue and three of its functional components: F1, the ATP hydrolytic unit; Fo, the oligomycin-sensitive conferring unit; and 1, a small peptide inhibitor of the ATPase. For these studies we use mitochondria from rat liver because much is known about the mitochondrial inner membrane from this tissue; because we have purified the oligomycin-sensitive ATPase complex and its F1 components from this tissue; because we have shown that many hepatoma mitochondria are defective in their capacity to hydrolyze ATP in the presence of an uncoupling agent; and because we have shown that in rapidly growing hepatoma mitochondria, Glc-6-P formation via hexokinase localized in the outer mitochondrial membrane is coupled to ATP synthesis in the inner mitochondrial compartment. The research currently being conducted in this laboratory is very necessary and fundamental to a complete understanding of energy coupling and utilization in both normal and transformed cells.